US9488672B2 - Dual channel accelerometer and method of manufacturing the same - Google Patents

Dual channel accelerometer and method of manufacturing the same Download PDF

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Publication number
US9488672B2
US9488672B2 US14/219,369 US201414219369A US9488672B2 US 9488672 B2 US9488672 B2 US 9488672B2 US 201414219369 A US201414219369 A US 201414219369A US 9488672 B2 US9488672 B2 US 9488672B2
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United States
Prior art keywords
piezoelectric elements
accelerometer
supporting base
seismic mass
output
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Expired - Fee Related, expires
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US14/219,369
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US20140305133A1 (en
Inventor
Andrew Peter MACDONALD
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Rolls Royce PLC
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Rolls Royce PLC
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
    • G01P15/00—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration
    • G01P15/02—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses
    • G01P15/08—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values
    • G01P15/09—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values by piezoelectric pick-up
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02C—GAS-TURBINE PLANTS; AIR INTAKES FOR JET-PROPULSION PLANTS; CONTROLLING FUEL SUPPLY IN AIR-BREATHING JET-PROPULSION PLANTS
    • F02C9/00—Controlling gas-turbine plants; Controlling fuel supply in air- breathing jet-propulsion plants
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
    • G01P15/00—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration
    • G01P15/02—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
    • G01P15/00—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration
    • G01P15/02—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses
    • G01P15/08—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values
    • G01P15/09—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values by piezoelectric pick-up
    • G01P15/0907—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values by piezoelectric pick-up of the compression mode type
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T29/00—Metal working
    • Y10T29/42—Piezoelectric device making

Definitions

  • the present invention relates to accelerometers and particularly, but not exclusively, to dual channel accelerometers together with methods of manufacturing the same.
  • Accelerometers are used for measuring levels of vibration in many different types of machinery. In many applications, such as for example aircraft engines, there is a need for duplicate measurements of vibration level in order to provide a level of redundancy in case of sensor failure.
  • FIG. 1 One such arrangement 10 , shown in FIG. 1 , employs two single channel accelerometers 12 , 14 mounted side by side within a common housing 22 . This has the advantage of being simple and is therefore a low cost solution.
  • twisting or flexure of the baseplate 20 on which the two accelerometers 12 , 14 are mounted further exacerbates the difference in vibration input to each of the accelerometers 12 , 14 .
  • consistent channel-to-channel matching is difficult to achieve.
  • An alternative arrangement 30 shown in FIG. 2 , is to position the two single channel accelerometers 32 , 34 on top of each other. This arrangement has the advantage that both accelerometers 32 , 34 now experience the same vibration input. However, differences remain between the vibration inputs to each of the two accelerometers 32 , 34 .
  • a dual output accelerometer having first and second output channels, comprising:
  • a piezoelectric sensing element commonly comprises a plurality of discs of piezoelectric material that are stacked together, usually with a common centre peg co-locating the discs together.
  • the individual discs of piezoelectric material making up two sensing elements are separated and then interleaved with one another and co-located with a single seismic mass.
  • any variation in vibration input resulting from the bending of the stack of piezoelectric elements will be distributed over the first and second piezoelectric elements. This will improve the channel-to-channel matching of the first and second transducers over a dual channel accelerometer of the prior art.
  • the first output channel is connected to the plurality of inter-connected first piezoelectric elements
  • the second output channel is connected to the plurality of inter-connected second piezoelectric elements.
  • Each of the first output channel and second output channel comprises signals generated from a plurality of individual respective first and second piezoelectric elements that are distributed over the length of the stack of piezoelectric elements. This reduces the adverse influence of out-of-plane movement of the dual channel accelerometer on the channel-to-channel matching of the first and second output signals.
  • each of the first piezoelectric elements and the second piezoelectric elements are alternately interleaved with one another.
  • the first and second channels receive signal contributions from the entire length of the sensing element stack. This minimises the influence of bending of the sensing stack on the channel-to-channel matching of the first and second output signals. This in turn provides for closer matching between the first and second output signals thereby improving the redundancy of the dual channel accelerometer.
  • the interleaving of first and second piezoelectric elements may take other interleaving patterns.
  • the stack of piezoelectric elements may comprise, in sequence, two first piezoelectric elements, one second piezoelectric element, one first piezoelectric element and two second piezoelectric elements. This sequence may itself then be repeated.
  • This asymmetric arrangement may be utilised to provide an indication of ‘out of plane’ movements while still providing a balanced and matched measure of in-plane accelerations.
  • the quantity of first piezoelectric elements is equal to the quantity of second piezoelectric elements.
  • first and second piezoelectric elements simplifies the calibration of the dual channel accelerometer.
  • first piezoelectric elements are formed from a first piezoelectric material while the second piezoelectric elements are formed from a second piezoelectric material.
  • the interleaving arrangement will still help to reduce variations in mechanical input to the individual stacks.
  • the first piezoelectric material may be selected for improved high frequency response while the second piezoelectric material may be selected for improved low frequency response. This would allow the first piezoelectric elements to provide a primary measurement of acceleration at high frequencies with the second piezoelectric elements providing a corresponding secondary ‘cross-check’ measurement. Likewise the second piezoelectric elements would then be used for a primary measurement of acceleration at low frequencies with the first piezoelectric elements acting as a secondary ‘cross-check’ measure.
  • the material properties (electromechanical coupling coefficient, electrical impedance, acoustic impedance, etc.) of the first and second piezoelectric materials will be different to one another and thus the quantity of first piezoelectric elements may differ from the quantity of second piezoelectric elements.
  • the dual channel accelerometer further comprises a casing fixed to the supporting base.
  • the casing protects the first and second transducers from mechanical and environmental damage.
  • the seismic mass comprises the rigid mechanical coupling between the co-located first and second piezoelectric elements and the supporting base.
  • the rigid mechanical coupling is a threaded fastener, the threaded fastener passing through the co-located first and second piezoelectric elements, and being threadingly connected to the supporting base.
  • a method of manufacturing a dual channel accelerometer comprising the steps of:
  • the dual channel accelerometer further comprises first and second output channels, the method comprising the further steps of:
  • each of the first piezoelectric elements and the second piezoelectric elements are alternately interleaved with one another.
  • the rigid mechanical coupling is integrally formed with the seismic mass.
  • a gas turbine engine comprising a dual output accelerometer as claimed in either of first and second aspects of the invention, and an engine control system connectable to both output channels of the dual output accelerometer.
  • aspects of the invention provide devices, methods and systems which include and/or implement some or all of the actions described herein.
  • the illustrative aspects of the invention are designed to solve one or more of the problems herein described and/or one or more other problems not discussed.
  • FIG. 1 shows a schematic sectional view of a dual channel accelerometer according to the prior art
  • FIG. 2 shows a schematic sectional view of an alternative dual channel accelerometer according to the prior art
  • FIG. 3 shows a schematic sectional view of a dual channel accelerometer according to a first embodiment of the invention.
  • FIG. 4 shows a schematic sectional view of a dual channel accelerometer according to a second embodiment of the invention.
  • a dual channel accelerometer according to a first embodiment of the invention is designated generally by the reference numeral 100 .
  • the dual channel accelerometer 100 comprises a supporting base 110 , a first transducer 120 , a second transducer 130 and a seismic mass 140 .
  • the first transducer 120 , second transducer 130 and seismic mass 140 are co-located on the supporting base 110 .
  • the supporting base 110 is fabricated from steel sheet, although any material having the requisite strength and stiffness properties might alternatively be used.
  • the seismic mass 140 is formed from steel with its mass and geometry being selected in accordance with the level of vibration which the dual channel accelerometer 100 is intended to be measuring as well as the sensitivity of the individual piezo-electric sensing elements. These selection criteria are well known in the art and are not repeated herein.
  • the first transducer 120 comprises a plurality of first piezoelectric elements 122 each of which is interconnected by first connectors 124 .
  • a first output channel 126 is connected to the plurality of interconnected first piezoelectric elements 122 .
  • the second transducer 130 comprises a plurality of second piezoelectric elements 132 each of which is interconnected by second connectors 134 .
  • a second output channel 136 is connected to the plurality of interconnected second piezoelectric elements 132 .
  • each of the first piezoelectric elements 122 and second piezoelectric elements 132 are alternately interleaved with one another.
  • An isolating washer (not shown) is interposed between each adjoining first and second piezoelectric elements 122 , 132 .
  • the co-located first transducer 120 , second transducer 130 and seismic mass 140 are secured to the supporting base 110 by the threaded fastener 150 .
  • Each of the first piezoelectric elements 122 , second piezoelectric elements 132 and seismic mass 140 has a central hole (not shown) to accommodate a threaded fastener 150 .
  • the threaded fastener 150 is a threaded stud that is screwed into a correspondingly threaded hole in the supporting base 110 .
  • the first and second piezoelectric elements 122 , 132 and the seismic mass 140 are located on the threaded stud and secured in place by a nut and washer.
  • the threaded fastener 150 may take the form of a bolt that passes through the centre hole in each of the seismic mass 140 and the first and second piezoelectric elements 122 , 132 .
  • the bolt is threadingly received in a corresponding threaded hole in the supporting base 110 .
  • a casing 160 is provided to enclose the co-located first transducer 120 , second transducer 130 and seismic mass 140 .
  • the casing 160 is formed from sheet metal and is secured to the supporting base 110 by, for example, crimping, welding or brazing its edges to the supporting base 110 .
  • a dual channel accelerometer according to a second embodiment of the invention is designated generally by the reference numeral 200 .
  • Features of the dual channel accelerometer 200 which correspond to those of apparatus 100 have been given corresponding reference numerals for ease of reference.
  • the dual channel accelerometer 200 comprises a supporting base 110 , a first transducer 220 , a second transducer 230 and a seismic mass 140 .
  • the first transducer 220 , second transducer 230 and seismic mass 140 are co-located on the supporting base 110 .
  • each of the first and second transducers 220 , 230 comprises a plurality of respective first and second piezoelectric elements 122 , 132 .
  • first and second piezoelectric elements 122 , 132 are stacked onto the supporting base 110 in a 2-1-1-2 arrangement.
  • two first piezoelectric elements 122 are initially positioned on the supporting base 110 , followed by a single second piezoelectric element 132 , a further single first piezoelectric element 122 and then two second piezoelectric elements 132 .
  • This 2-1-1-2 series may then itself be repeated, for example as shown in FIG. 4 .
  • each of the first piezoelectric elements 122 are interconnected by first connectors 124
  • each of the second piezoelectric elements 132 are interconnected by second connectors 134 .
  • the interconnected first piezoelectric elements 122 provide a signal output to a first output channel 126
  • the interconnected second piezoelectric elements 132 provide a signal output to a second output channel 136 .
  • Assembly of the dual channel accelerometer 100 : 200 follows the same procedure for both of the first and second embodiments.
  • the interleaved stack of first piezoelectric elements 122 and second piezoelectric elements 132 is positioned over a threaded stud which is attached to the supporting base 110 .
  • An isolating washer is placed between each pair of adjoining piezoelectric elements 122 , 132 .
  • the seismic mass 140 is then positioned on the interleaved stack of first piezoelectric elements 122 and second piezoelectric elements 132 .
  • the seismic mass 140 and the first piezoelectric elements 122 and second piezoelectric elements 132 are secured to the supporting base 110 by attaching a nut to the threaded stud.
  • the dual channel accelerometer 100 : 200 is secured to a piece of equipment (not shown) for which it is desired to know the level of vibration experienced.
  • Each of the first output channel 126 and second channel 136 transmits a signal (not shown) to a signal processing apparatus (not shown) which then provides a user with a value for the level of vibration experienced by the dual channel accelerometer 100 : 200 and hence the piece of equipment.
  • the dual channel accelerometer 100 : 200 may be tuned by adding or removing material from the seismic mass 140 .

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Measurement Of Mechanical Vibrations Or Ultrasonic Waves (AREA)
  • Geophysics And Detection Of Objects (AREA)
US14/219,369 2013-04-15 2014-03-19 Dual channel accelerometer and method of manufacturing the same Expired - Fee Related US9488672B2 (en)

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GB1306757.4A GB2505737B (en) 2013-04-15 2013-04-15 Dual channel accelerometer and method of manufacturing the same
GB1306757.4 2013-04-15

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US9488672B2 true US9488672B2 (en) 2016-11-08

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10596903B2 (en) 2015-10-13 2020-03-24 Consumer Safety Technology, Llc Networked intoxication vehicle immobilization
US10663440B2 (en) 2016-09-09 2020-05-26 Consumer Safety Technology, Llc Secure data handling in a breath alcohol calibration station
US10877008B2 (en) 2016-09-09 2020-12-29 Consumer Safety Technology, Llc Reference gas management in a breath alcohol calibration station
US12311759B1 (en) 2022-02-02 2025-05-27 Consumer Safety Technology, Llc Wireless vehicle interface for immobilization system

Citations (8)

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Publication number Priority date Publication date Assignee Title
US3566163A (en) * 1967-09-05 1971-02-23 Kistler Instrumente Ag Multiple-component piezomeasuring cells
US4586377A (en) 1983-02-21 1986-05-06 Vibro-Meter Sa Dual accelerometer, method for its fabrication and application thereof
WO1988007664A1 (fr) 1987-03-30 1988-10-06 Lew Hyok S Detecteur d'impulsions avec preamplification mecanique et elimination du bruit
EP0316498A1 (fr) 1987-11-09 1989-05-24 Vibro-Meter Sa Accéléromètre
US6655211B1 (en) * 2000-03-08 2003-12-02 Vibro-Meter Sa Piezoelectric accelerometer with laterally stabilizing element
GB2492798A (en) 2011-07-12 2013-01-16 Weston Aerospace Ltd Dual Output Accelerometer System
US9057655B2 (en) * 2012-08-31 2015-06-16 Meggitt Sa Force sensor and method for testing its reliability
US9217680B2 (en) * 2011-12-20 2015-12-22 Seiko Epson Corporation Sensor device, sensor module, robot and method of manufacturing sensor device

Patent Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3566163A (en) * 1967-09-05 1971-02-23 Kistler Instrumente Ag Multiple-component piezomeasuring cells
US4586377A (en) 1983-02-21 1986-05-06 Vibro-Meter Sa Dual accelerometer, method for its fabrication and application thereof
WO1988007664A1 (fr) 1987-03-30 1988-10-06 Lew Hyok S Detecteur d'impulsions avec preamplification mecanique et elimination du bruit
EP0316498A1 (fr) 1987-11-09 1989-05-24 Vibro-Meter Sa Accéléromètre
US5052226A (en) 1987-11-09 1991-10-01 Vibro-Meter Sa Accelerometer with piezoelectric element
US5117696A (en) 1987-11-09 1992-06-02 Vibro Meter Sa Biaxial accelerometer
US6655211B1 (en) * 2000-03-08 2003-12-02 Vibro-Meter Sa Piezoelectric accelerometer with laterally stabilizing element
GB2492798A (en) 2011-07-12 2013-01-16 Weston Aerospace Ltd Dual Output Accelerometer System
US9164122B2 (en) * 2011-07-12 2015-10-20 Weston Aerospace Limited Dual output accelerometer system
US9217680B2 (en) * 2011-12-20 2015-12-22 Seiko Epson Corporation Sensor device, sensor module, robot and method of manufacturing sensor device
US9057655B2 (en) * 2012-08-31 2015-06-16 Meggitt Sa Force sensor and method for testing its reliability

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Title
Search Report issued in British Application No. 1306757.4 dated Oct. 29, 2013.
Search Report issued in European Patent Application No. 14 16 0488 dated Jun. 23, 2014.

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10596903B2 (en) 2015-10-13 2020-03-24 Consumer Safety Technology, Llc Networked intoxication vehicle immobilization
US10604011B2 (en) 2015-10-13 2020-03-31 Consumer Safety Technology, Llc Networked intoxication vehicle immobilization
US12054044B2 (en) 2015-10-13 2024-08-06 Consumer Safety Technology, Llc Networked intoxication vehicle immobilization
US11338675B2 (en) 2015-10-13 2022-05-24 Consumer Safety Technology, Llc Networked intoxication vehicle immobilization
US10919389B2 (en) 2015-10-13 2021-02-16 Consumer Safety Technology, Llc Networked vehicle immobilization
US11047840B2 (en) 2016-09-09 2021-06-29 Consumer Safety Technology, Llc Reference gas management in a breath alcohol calibration station
US10948468B2 (en) 2016-09-09 2021-03-16 Consumer Safety Technology, Llc Fault-tolerant breath alcohol calibration station and method
US10877008B2 (en) 2016-09-09 2020-12-29 Consumer Safety Technology, Llc Reference gas management in a breath alcohol calibration station
US11415564B2 (en) 2016-09-09 2022-08-16 Consumer Safety Technology, Llc Secure data handling in a breath alcohol calibration station
US11971395B2 (en) 2016-09-09 2024-04-30 Consumer Safety Technology, Llc Secure data handling in a breath alcohol calibration station
US10663440B2 (en) 2016-09-09 2020-05-26 Consumer Safety Technology, Llc Secure data handling in a breath alcohol calibration station
US12241879B2 (en) 2016-09-09 2025-03-04 Consumer Safety Technology, Llc Reference gas management in a breath alcohol calibration station
US12339263B2 (en) 2016-09-09 2025-06-24 Consumer Safety Technology, Llc Detection device transfer system
US12311759B1 (en) 2022-02-02 2025-05-27 Consumer Safety Technology, Llc Wireless vehicle interface for immobilization system

Also Published As

Publication number Publication date
EP2793032B1 (fr) 2015-04-29
GB2505737B (en) 2016-04-06
US20140305133A1 (en) 2014-10-16
EP2793032A1 (fr) 2014-10-22
GB2505737A (en) 2014-03-12
GB201306757D0 (en) 2013-05-29

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